Process for the production of 2-aryl-2H-1,2,3-triazoles

Abstract

4-Akylthiomethyl-2-aryl-2H-1,2,3-triazoles and 4-arylthiomethyl-2-aryl-2H-1,2,3-triazoles are produced from γ-chloroacetoacetyl chloride, aryldiazonium salts and thiolates. In a first step, the aryldiazonium salt is reacted with the chloroacetoacetyl chloride to the corresponding 3-chloropyruvaldehyde-arylhydrazone, which is converted with the thiolate into the corresponding 3-alkylthio or 3-arylthiopyruvaldehyde-arylhydrazone. The 3-alkylthio or 3-arylthiopyruvaldehyde-arylhydrazone is cyclized with hydroxylamine-O-sulfonic acid to the desired 2-aryl-2H-1,2,3-triazole.

What is claimed is: 
     
       1. A process for the production of a 2-aryl-2H-1,2,3-triazole of the formula: ##STR6## wherein R 1  is a member selected from the group consisting of phenyl, o-methylphenyl, m-methylphenyl, p-methylphenyl, o-chlorophenyl, m-chlorophenyl, p-chlorophenyl, o-nitrophenyl, m-nitrophenyl, p-nitrophenyl, o-methoxyphenyl, m-methoxyphenyl, p-methoxyphenyl, a dimethylphenyl, a dichlorophenyl, a chloromethylphenyl, a nitromethylphenyl, a side-chain halogenated alkylphenyl, and a dichloro-trifluoromethylphenyl, and R 2  is a member of the group consisting of a branched alkyl group, an open chain alkyl group and a cyclic alkyl group, characterized in that γ-chloroacetoacetyl chloride: ##STR7## in a first step, is coupled with a diazonium salt of the formula: ##EQU3## wherein R 1  has the above-mentioned meaning, n is 1 to 2, and A n-   is an anion of a monobasic strong acid or a multibasic strong acid, to the corresponding 3-chloropyruvaldehyde arylhydrazone of the formula: ##STR8## wherein R 1  has the above-mentioned meaning, in a second step, the 3-chloropyruvaldehyde arylhydrazone of the formule IV, is reacted with a thiolate of the formuls:   Y.sup.+  R.sup.2 S.sup.-     wherein R 2  has the above-mentioned meaning, and Y +   is hydrogen or an alkali metal cation, to the corresponding 3-substituted pyruvaldehyde arylhydrazone of the formula: ##STR9## wherein R 1  and R 2  have the above-mentioned meaning, and, finally, in a third step, 3-substituted pyruvaldehyde arylhydrazone of the formula V is cyclized with hydroxylamine-O-sulfonic acid to said 2-aryl-2H-1,2,3-triazole of the formula I.   
     
     
       2. The process according to claim 1 wherein R 1  is 2,6-dichloro-4-trifluoromethyl-phenyl. 
     
     
       3. The process according to claim 1 wherein a diazonium salt wherein A n-   is chloride or hydrogen sulfate, is used. 
     
     
       4. The process according to claim 3 wherein the diazonium salt is produced by diazotization of the corresponding amine with nitrosylsulfuric acid. 
     
     
       5. The process according to claim 4 wherein a sodium alkylthiolate is used as the thiolate. 
     
     
       6. The process according to claim 5 wherein a methanethiolate is used as the thiolate. 
     
     
       7. The process according to claim 6 wherein the reaction of 3-chloropyruvaldehyde-arylhydrazone is performed with the thiolate at 0° to 40° C. in a protic or polar aprotic solvent. 
     
     
       8. The process according to claim 7 wherein the cyclization is performed with hydroxylamine-O-sulfonic acid in an aqueous organic solvent system, in that the substituted pyruvaldehyde-arylhydrazone is reacted first with sulfonic acid at a temperature below 40° C. and then the pH of the reaction mixture is adjusted with a base to a value of 6 to 8 and the mixture is optionally heated to a temperature up to 80° C. 
     
     
       9. The process according to claim 8 wherein an acetonitrile-water mixture is used as the aqueous-organic solvent system. 
     
     
       10. The process according to claim 9 wherein 2,6-dichloro-4-trifluoro-methylbenzenediazonium hydrogen sulfate is used as the diazonium salt. 
     
     
       11. The process according to claim 1 wherein the diazonium salt is produced by diazotization of the corresponding amine with nitrosylsulfuric acid. 
     
     
       12. The process according to claim 1 wherein a sodium alkylthiolate is used as the thiolate. 
     
     
       13. The process according to claim a methanethiolate is used as the thiolate. 
     
     
       14. The process according to claim 1 wherein the reaction of 3-chloropyruvaldehyde-arylhydrazone is performed with the thiolate at 0° to 40° C. in a protic or polar aprotic solvent. 
     
     
       15. The process according to claim 1 wherein the cyclization is performed with hydroxylamine-O-sulfonic acid in an aqueous organic solvent system, in that the substituted pyruvaldehyde-arylhydrazone is reacted first with sulfonic acid at a temperature below 40° C. and then the pH of the reaction mixture is adjusted with a base to a value of 6 to 8 and the mixture is optionally heated to a temperature up to 80° C. 
     
     
       16. The process according to claim 15 wherein an acetonitrile-water mixture is used as the aqueous-organic solvent system. 
     
     
       17. The process according to claim 1 wherein 2,6-dichloro-4-trifluoro-methylbenzenediazonium hydrogen sulfate is used as the diazonium salt. 
     
     
       18. The process according to claim 1 wherein n is 1 and m is 1.